States of ${}^{12}$N with enhanced radii

Abstract

The differential cross sections of the ${}^{12}$C(${}^3$He,t)${}^{12}$N reaction leading to formation of the 1${}^{+}$ (ground state), 2${}^{+}$(0.96 MeV), 2${}^{-}$(1.19 MeV), and 1${}^{-}$(1.80 MeV) states of ${}^{12}$N are measured at $E$(${}^3$He)=40 MeV. The analysis of the data is carried out within the modified diffraction model (MDM) and distorted wave Born approximation (DWBA). Enhanced $rms$ radii were obtained for the ground, 2${}^{-}$(1.19 MeV), and 1${}^{-}$(1.80 MeV) states. We revealed that ${}^{12}$B, ${}^{12}$N, and ${}^{12}$C in the IAS with T=1, and spin-parities 2${}^{-}$ and 1${}^{-}$ have increased radii and exhibit properties of neutron and proton halo states.

Comments: 6 pages, 4 figures, 2 tables